Concrete floating docks and breakwaters, such as described in U.S. Pat. No. 4,318,361 to Sluys, have been assembled from a series of concrete modules. The modules typically comprise either a hollow concrete shell or a concrete shell surrounding a buoyant foam core. For use as a breakwater or a dock, the assemblage of modules are typically connected at one or both ends to an anchoring point, such as a driven piling or a weighted anchor. As a breakwater, the assemblage of modules is intended to absorb or reflect the incident wave energy and thereby provide a sheltered area of relatively calm water for the mooring of boats.
When used as a dock, the assemblage of modules may be fitted with a suitable decking material or the upper exposed concrete surface may be provided with a slip resistant finish. It may be desirable to have the incident wave energy pass unimpeded through open portions of the dock so that the dock remains relatively stable. Open portions between adjacent modules may also be desirable to allow floating debris to pass therethrough and avoid the unsightly accumulation of the debris.
Interconnecting of the modules for a concrete dock or breakwater has been accomplished in a number of ways. For example, U.S. Pat. No. 4,693,631 to McKay discloses a pair of longitudinal strips running alongside and secured to the upper opposing sides of adjacent modules. In a similar fashion, U.S. Pat. No. 4,709,647 to Rytand discloses opposing inner and outer sidewales, preferably formed of wood, for maintaining adjacent modules in alignment while leaving a one or two foot gap therebetween.
However, interconnection of adjacent floatation modules at the top portion allows the modules to pivot relative to one another. Such pivotal movement places high stress forces on any interconnecting member and may subject such a member to premature failure. In addition, the pivoting motion provides a less effective inertial barrier to the wave action and also creates an unstable surface for dock users. If the bottom portions of adjacent modules collide during the pivoting movement, damage to the modules is likely.
U.S. Pat. No. 4,321,882 to Sluys discloses chains or cables passing through two internal passageways in a series of modules with a pair of resilient spacers positioned between adjacent modules. The modules are thus allowed to move pivotally with respect to one another. The pivotal movement of adjacent modules places considerable stress on the resilient spacers and may result in increased maintenance expense for repairing damaged or worn resilient spacers. The pivoting provides a less effective inertial barrier to the wave action and also may create an unstable surface for dock users. The pivoting action about a center point may damage both the top and bottom of adjacent modules when these portions collide as a result of wave action.